Ministers may have known almost a year ago there was a strain of influenza circulating which the flu vaccine would not protect against, the Prime Minister's official spokesman has suggested.The spokesman said Government officials "work closely" with the World Health Organisation (WHO), which on Friday said the newly emerged virus was first detected in “late-March 2014”.It raises serious questions about why millions of elderly Britons who took the flu jab over the winter were not warned that they remained unprotected to certain strains.Public Health England has admitted that the vaccine barely works and could bring the largest number of winter deaths in 15 years.New figures show that there was ‘significant excess mortality’ in the over-65s for the eighth week running, linked to the ineffective flu jab and recent cold snap.

The Prime Minister’s official spokesman was quizzed about the WHO’s announcement that it first detected the strain in later March and asked when the Government first became aware. “They work closely with the World Health Organisation on it,” the spokesman said. They noted Public Health England has said it was aware of the new strain emerging in Australia in August. Asked whether the Prime Minister thinks there should be a review into the handling of the flu jab, the spokesman said: "He thinks that the vaccine is still the best protection that we have and [we will] keep working on it." Dr John McCauley, of the Medical Research Council’s Institute for Medical Research said the World Health Organisation had detected the dangerous new strain in late March 2014 but was still unsure by the summer if it would become the predominant strain in the Northern Hemisphere. Yet experts said it was generally likely that southern strains would become dominant in the north. PHE warned that the main strain of influenza in circulation – which is particularly lethal among the elderly – has mutated from the type that was used in the jab. As a result, it is working in just three per cent of people given it, when it is normally effective in around half of cases. And it has no effectiveness at all against the dominant strain of flu in circulation this winter, which is particularly dangerous in the elderly. The current flu season has been dominated by circulation of influenza A (H3N2) subtype viruses. Dr McCauley said: “This newly emerged virus was first detected by the WHO Global Influenza Surveillance and Response System, a network of 142 laboratories in 112 countries around the world in late-March 2014, too late to be included in the vaccine. “Indeed, even through the summer months it was uncertain whether this new antigenically variant virus would predominate in the Northern Hemisphere winter (2014 – 2015) influenza season. “The emergence of this antigenically variant virus during the year shows how difficult it can be to always have the best influenza vaccine possible. Questions are being asked about why health officials had not raised the alarm earlier, with concern that the rising number of cases of flu in those who had been vaccinated was not properly tracked. Last month, after The Telegraph highlighted doctors’ concerns that mutations in the influenza virus were fuelling a rise in emergency hospital admissions, health officials said there was no evidence that the drift variant would become the dominant strain. Latest figures show that the number of “excess deaths” this winter – those caused by flu and cold weather – is one third higher than average. The new study found that the vaccine is protecting just 3.4 per cent of people from flu. Katherine Murphy, chief executive of the Patients Association, said the disclosures were “extremely worrying” for those who thought they were protected against flu. “It beggars belief that health officials weren’t aware just how badly the vaccine was working a long time ago,” she said. “If they didn’t realise the scale of the problem until now they aren’t doing their job properly.” However Dr Michael Skinner, Reader in Virology and Head of the Vaccine Vector Group at Imperial College London, said the length of time it takes to make and distribute vaccines means health experts have ‘one chance’ to get it right. “Although the virus was detected in March there was no real way of knowing whether it would become established as a significant player in the northern hemisphere in the winter,” said Dr Skinner. “Besides, the process takes 6 months or so, about half of that in the lab establishing the seed stocks and half in the vaccine plants. “Moreover, there are supply issues, so effectively you get one chance per year. If you delay, say to restart with a new virus, then even if you managed to produce as much, you probably wouldn’t be able to roll it out through GPs and clinics in time for the season.” Dr Skinner said the flu vaccine still protected people against two strains and said to label it useless was ‘misguided.’